1. Field of the Invention
The present invention relates to the measurement of time in general, and more particularly to the automatic determination of local time using direct observations of the sun.
More specifically, this invention relates to methods and apparatus for automatically carrying out the determination of lapsed time measurements of the rotation of the surface of a planet in relation to its daily and annual position with its sun.
2. Description of the Prior Art
Devices for determining time by primary reference to sun sightings are, of course, as old as time keeping itself. From the days of the earliest sun dials to the present however, the use of devices and methods for time determination which employ sun observations of all types have required a fair degree of knowledge and agility on the part of the users. These requirements virtually assured that time keeping by sun observations would be largely limited to use by scientists, scholars, and others trained in the setting up, calibrating and interpreting of the means employed.
Simple prior art devices arranged such that a minimum amount of skill would be required for their use invariably suffer from deteriorated accuracy. Exemplary early prior art devices of highly simple configurations are provided in U.S. Pat. No. 1,630,891 to Cooke and in 1,570,349 to Hollingwood. Even given the primitive nature of the devices disclosed therein, it is required that the user manipulate various planes, to insert at least latitude, and perform other approximations prior to use. More recent devices, such as that taught in U.S. Pat. No. 3,940,859 to Troseth, also require a good deal of manual manipulation on the part of the user and, as with most other devices wherein the equation of time is reduced to graphical indicia, suffers from a time reading of only modest accuracy.